Demographic data from Census 2000 are tabulated for the types of geographic areas shown in the following
graphic. This section summarizes some of the key geographic terms and definitions related to Census 2000.
Understanding the definition and use of these geographic areas (for tabulation purposes) is key to knowing
how to access what types of subject matter.

Census 2000 Geographic Tabulation Areas

Geographic Areas & Census 2000. The following types of geographic areas are reviewed in this section.

State and county area names and codes used in Census 2000 tabulations are
available in the Geographic Identification Code Scheme.
State and county geocodes are often used with
geocodes for smaller geographic areas (e.g., census tracts) as unique, short-hand, standardized identifiers.

Since Census 2000, a new set of official definitions for metropolitan statistical areas (MSAs) have been established
by OMB. The initial Census 2000 MSA tabulations were based on the "1999 vintage" MSA definitions.
In 2003, the new "2003 vintage" MSA definitions were established.

The geographic definitions (as of June 30, 1999) used for tabulating Census 2000
metropolitan areas are available in these lists:

Very limited scope Census 2000 demographic data have been tabulated by the Census Bureau for
2003 vintage MSAs.
See 2003 Vintage Metropolitan Statistical Areas for more detailed information about current
official metropolitan statistical areas.

School district geography for Census 2000 tabulations corresponds
to the 1999-2000 school year. Learn more about accessing school district data via the
School District Demographics Web page.

There are some school district tabulation areas that are not officially Federal school districts.
Major exceptions are in Hawaii and New York which
have school district tabulation areas that have been specially defined and are not
Federal public school districts. In addition, there are "balance of county" areas for earth surface areas
not covered by any school district.

Census Tracts

The census tract (averaging approximately 4,000 population) is the smallest unit of geography for which
'more extensive and more reliable' sample-based (short-form) data are available.
It is not possible to aggregate census tract units to all other types of geographic
tabulation areas (see graphic at top of this section).

The census block group (averaging approximately 1,000 population) is the smallest unit of geography for which sample-based (short-form) data were tabulated.
It is not possible to aggregate block group units to all other types of geographic
tabulation areas (see graphic at top of this section).

See Proximity Demographic Profile Database for information for the most widely used
readily accessible block group level data.
These data may be easily integrated into shapefiles for mapping applications.

Census Blocks

The census block is smallest unit of geography for
which Census 2000 data are tabulated (see graphic at top of this section).
Census block data may be aggregated into any of the higher level geographic levels/areas.
Census block data are only available for items covered on the complete count questionnaire.

See Proximity Census Block Database for information for the most widely used readily accessible block
level data. These data may be easily integrated into shapefiles for mapping applications.

ZIP Code Tabulation Areas

ZIP Code Tabulation Areas (ZCTA) closely approximate U.S. Postal Service ZIP Code areas.
It is not possible to aggregate ZCTA units to most other types of geographic
tabulation areas (see graphic at top of this section).

See Demographic Profile Database for information for the most widely used
readily accessible ZCTA level data.
These data may be easily integrated into shapefiles for mapping applications.

Classifications of urban and rural geography changed with Census 2000.
Urbanized areas are similarly defined as with the 1990 Census but urban clusters are new.
Urbanized areas and urban clusters combined are the "urban areas."
Areas not classified as urban are rural.

1990 Census. In the 1990 Census, "urban" refers to all territory, population, and housing units in
urbanized areas and in places of 2,500 or more persons outside
urbanized areas:

Places of 2,500 or more persons incorporated as cities,
villages, boroughs (except in Alaska and New York), and
towns (except in the six New England States, New York,
and Wisconsin), but excluding the rural portions of
"extended cities."

Census designated places of 2,500 or more persons.

Other territory, incorporated or unincorporated,
included in urbanized areas.

"Rural" refers to territory, population, and housing units not classified as
urban. In 1990 Census 100-percent (complete count) data products,
"rural" is divided into "places of less than 2,500" and "not in
places." The "not in places" category comprises "rural" outside
incorporated and census designated places and the rural portions
of extended cities. In many data products, the term "other
rural" is used; "other rural" is a residual category specific to
the classification of the rural in each data product.

In 1990 Census sample data products, rural population and housing
units are subdivided into "rural farm" and "rural nonfarm."
"Rural farm" comprises all rural households and housing units on
farms (places from which $1,000 or more of agricultural products
were sold in 1989); "rural nonfarm" comprises the remaining
rural.

The urban and rural classification cuts across the other
hierarchies; for example, there is generally both urban and rural
territory within both metropolitan and nonmetropolitan areas.

See
this URL for a description of related historical data available from
decennial censuses:

Census 2000. For Census 2000, urban/rural criteria/classifications differ some from
previous censuses. Urbanized areas are similarly defined as with the 1990 Census but urban clusters are new.
Urbanized areas and urban clusters combined are the "urban areas."
Areas not classified as urban are rural.